The present invention relates to an electronic control device for electric ranges having a digital input for switching the effective power associated with individual heat settings, or "heat values" for each heating element of the range, by means of switching pulses having different on-off ratios.
An electric range is known which has an electronic switching device, as described, for example, in an information pamphlet published by the firm Frigidaire, entitled "Cook-N-Care Guide For Your New Frigidaire Touch-N-Cook Range", in which the term "heat values" is employed to refer to the different heat settings of a surface heating unit. In such a range, the heat of the surface heating units and of the oven are regulated in such a manner that the individual heat settings have associated with them different effective power levels resulting from the production of switching pulses of different on-off, or duty, ratios, or ratios of switch-on time to switch-on time + switch-off time. This is accomplished in that the control device varies the length of the switch-on pulse as well as the length of the interval period between switch-on pulses for different heat settings. The switch-on period within the individual heat settings extends from 10 to 100% of each on-off cycle in this case.
In the known control device it is not possible to start cooking with full power at the lower heat settings so that for the start of cooking with full power the highest setting must first be used. Upon completion of the start of cooking period, the range must again be switched to a lower effective power at a lower heat setting in order to finish the cooking or baking. Due to the long pauses when no power is being delivered at the lower heat settings, the temperature of the food being cooked fluctuates within such wide limits that no constant temperature can be attained.